/Engine/Source/Runtime/HeadMountedDisplay/Public/HeadMountedDisplayTypes.h
Flags to better inform the user about specifics of the underlying XR system
namespace EXRSystemFlags { enum Type { NoFlags = 0x00, IsAR = 0x01, IsTablet = 0x02, IsHeadMounted = 0x04, SupportsHandTracking = 0x08, } }